1. Technical Field
The present disclosure relates to a surgical fastening apparatus and, more particularly, to a surgical fastening apparatus having a fastener and retainer system.
2. Background of the Related Art
Various types of surgical stapling instruments for performing a circular anastomosis are well known, wherein an operator actuates the apparatus at a location which is relatively remote from the location at which the circular anastomosis takes place. Anastomosis is the surgical joining of separate hollow organ sections. Typically, an anastomosis procedure involves surgery in which a diseased or defective section of hollow tissue is removed.
A conventional surgical stapling instrument for performing a circular anastomosis in a hemorrhoidal or other surgical procedure generally includes a shell assembly having an annular array of staples and staple slots and an anvil assembly having a circular array of staple forming pockets in a proximal surface thereof. An example of surgical stapling instruments for performing circular anastomosis is described in U.S. Pat. Nos. 7,168,604, 7,303,106 and pending U.S. application Ser. No. 12/550,443, filed Aug. 31, 2009, all of which are incorporated herein in their entirety by reference. Typically, the anvil assembly is longitudinally movable from an open position to a closed position which places the anvil assembly adjacent to the shell assembly to clamp the body tissue therebetween. After bringing the anvil and shell assemblies to a closed position to clamp tissue, an annular pusher including a plurality of pushers which are configured to eject a corresponding staple from the staple slot through the tissue and against a receiving pocket of the anvil to form staples is actuated by the operator in a relatively remote region to perform a circular anastomosis. After stapling the tissues together, the tissue is severed by the annular blade and extracted.
Surgical fastening instruments applying two part surgical fasteners are known. In these instruments, a plurality of retainers are supported in an anvil assembly and a plurality of fasteners are supported in a fastener holding assembly. The fasteners are advanced through tissue and into engagement with openings in respective retainers. These two part fasteners are typically composed of resorbable material. The firing force of the fasteners in some of these instruments could shift the retainers out of position which may result in misalignment. In addition, the retainers may slip against the anvil and/or may come off the anvil before firing which may also result in misalignment. Accordingly, it would be advantageous to provide a configuration which enhances mating of the fasteners and the retainers and it may be useful to provide such configuration in a circular anastomosis instrument.
Additionally, the thickness of the clamped tissue can vary in different regions. Therefore, it would be advantageous to provide a fastener-retainer configuration which can accommodate such varying tissue thickness.